(a) Field of the Invention
The present invention relates to a method for forming an interconnection in a semiconductor device, and more particularly to a method for forming a dual damascene interconnection in a semiconductor device.
(b) Description of the Related Art
Recently, known dual damascene processes have been used to overcome difficulties arising from dry etching of copper interconnections, which have electrical characteristic superior to aluminum (Al) or tungsten (W) interconnections.
In the known dual damascene process, a via hole and a trench are formed, and the via hole and trench are filled with a copper film.
FIGS. 1 to 3 are sectional views illustrating a method for forming a conventional dual damascene interconnection.
As shown in FIG. 1, first, an intermetal insulating film 120 is formed on an etch stop film 110 on a lower metal film 100, the lower metal film 100 configured to be interconnected. Subsequently, a mask pattern for via hole formation is formed on the intermetal insulating film 120. Thereafter, a via hole 130 is formed using the mask pattern.
Next, the mask pattern is removed, and a mask pattern is used to form a trench 140. When the via hole 130 and trench 140 are formed, a portion of a surface of the etch stop film 110 on the lower metal film 100 is exposed.
As shown in FIG. 2, a dry etching process is used to remove the exposed portion of the etch stop film 110. A CxFy gas is used as an etching gas. Polymers 150 are generated, however, on exposed surfaces of the lower metal film 100 and side walls of the intermetal insulating film 120.
As shown in FIG. 3, a diffusion barrier 160 is formed within the via hole 130 and trench 140 such that the diffusion barrier 160 contacts the exposed lower metal film 100. An upper metal film 170 is then formed on the diffusion barrier 160 such that the via hole 130 and the trench 140 are completely filled with the upper metal film 170.
Subsequently, a planarization process is performed to complete a dual damascene interconnection.
However, as discussed above, the conventional method for forming a conventional dual damascene interconnection results in the generation of the polymers 150 while the exposed portion of the etch stop film 110 is removed. The polymers 150 generally remain on the exposed surfaces of the lower metal film 100 and side walls of the intermetal insulating film 120, even after cleaning of the surfaces is attempted. The polymers 150 cause deterioration of contact resistance. In addition, water absorption by the polymers may result in corrosion of the lower metal film.